Electric furnace.



F. T. SNYDER.

` ELECTRIC FUBNACE. APPLICATION FILED SEPT. 25, 1906.

Patented Dec. 7, 1909.

P. T. SNYDER. l

` ELECTRIC rjURNAoB. APPLICATION FILED SEPT. 25, 1906.

2 SHEETB-BHEBT 2.

Patented Dec. 7, 1,909.

, will be especially adapted for usein connec` UNITED sTATEs PATENT oEEICE.

FREDERICK T. SNYDER, oF OAK PARK, ILLINOIS, AssIGNoR To ELECTRIC METALS COMPANY, OF CHICAGO, ILLINOIS, Al CORPORATION OF WEST VIRGINIA.

ELECTRIC FUR/NACE.

Specification of Letters Patent.

Patented Dec. 7, 1909.

Application filed September 25, 1906. Serial No. 336,186.

To all'whom it may concern: 4

Be it known that l, Fiucimiiicii T. SNYDER,

citizen of the lUnited States,I residing at (lak Park, in the county of Cook and State of illinois. have invented a cei'tain new and useful .Improvement in Electric Furnaces,

of which the following is a full, clear, concise, Vand exact description.

My invention relates to an 'electric furiiacc'lor the sineltiiig of ores, with especial ict'erence olores of ii'ietals which are volatile at reduction. Forcxample, my furnace will be especially useful for smelting Zinc ore, and in connection with such` ore one object of this invention is to adapt the fiirnace to the direct production of spelter, in-l stead-of '/.iuc dt St'.

l More specific atures of the invention re late to means for preventingeffects of selfvinduction due to the iron water-jacket, to

an improvi'fd construction of furnace which tion with a three-phase system of electrical distribution, to improved means for withdrawing the condensed volatile metal and maintaining the same in a suitably-heated condition, as well as for refining the metallic product and separately collecting the dif-- ferent metals; and to details-of constructionu looking toward strength, simplicity, durability, cheapness of construction, and ease and efficiency of operation.

L will describe the several features of this invention by referencerto the furnace shown in the accompanying drawings, in which 1 Figure l is a vertical sectional elevation of the furnace; Fig. 2 is' a sectional eleva- A'tion taken at right angles to Fig. l.. v Like parts are designated by similar letters .of i'efereiice in both figures.

The form of furnace shown in the drawings consists of a crucible base a of lirebrick'inasoiii'y, which is supported in an yiron caisson a', and this base is surinoiinted by a furi-iace chamber, the'walls whereof are made, of hollow iron Jackets or conduits I) .through which a flow of water is maintained. The furnace chamber is open at thelt'op to receive the charge and to permit the escape of uncondensed vapors. The water j ackets preferably extend clear to the top of the furnace to'cool the upper portion of vthe charge. W hen in operation, the

lower portion of the c rucible will contain` molten metal (sucly as lead) above which there will be moltenmatte and slag. The furnace illustrated is adapted for use with a three-phase system of electricaldistrbution". three carbon electrodes c being provided, which are suspended in uprightvpositions in the furnace chamber, extending down far enough to klip into th'e molten conducting material contained in the crucible. A removable hopper-Z is supported at the top of the furnace immediately surrounding the' electrodes, the side guide` plates d el of said hopperv being located between the electrodes and the side walls of the furnace. This hopper is adapt-ed to receive a special element of the charge, such as powdered coke, to be fed immediately around the electrodes, the inain body of the charge being fed into the'lurnace between the outer edges of the removable hopper and the side walls of the furnace.`

Aniinportant feature of this' invention is a construction of the furnace such that the volatile metallic product may be condensedl as a liquid and drawn off through the side cous products of reduction are allowed` to escape through the porous material of the kchargeand leave the furnace at the top, but

'walls of the furnace. The nou-metallic gaswill 'be completely filled by asinall stream of liquid` metal and the passage of any gas therethrough thus, efectually prevented. These tubes serve to condense any ine- Atallic vapor which may enter them; and I preferably surround eacli tube with anindependent water-jacket K to assist in keeping its temperature sufficiently low. On -the other hand, the tubes are sufficiently thick so that the heat-from the liquid metal passing through them will not be too quickly conducted away to the water-jacket, which would otherwise tend to freeze the metal and choke up the passage.

It will thus be seen that my invention contemplates a furnace in which the condensed volatile metal is withdrawn by a passage passages. lf desired, however, to close up one .of the outlet passages, this may be done very simply and easily by permitting a greater' fiow of cooling water around its individual water-jacket, which will result in freezing the metal in the passage. The passage maybe opened againwhen desired by lessening the fiow of water to permit the metal to melt out. `'lhe area of the outlet passages may thus be lcontrolled at will. 'flie'slag immediately in the vicinity of the electrodes is molten, but toward the waterljacketed walls of the furnace, it is cooler, ail is congealed on these walls to form a lining therefor. This lining is self-renewing and is kept from melting entirely away 'by the cooling effect of the flowing water'.

The lining extends up along the lower por; tion of the side walls liighfas the level of the molten slag reaches, and the upper edge or rim of the lining serves as a drain to collect .the liquid zine which has condensed on the upper portion of the wall and run down.-

The tubes forming the zinc outlets open just above the slag level, to receive and drain off the zinc which is collec-,ted by the slag rim.

The liquid Zinc or other metal discharged l from the tubes K is collected in wells fm, in

the base of the furnace.v These wells preferably coinmunicate'witli the lower portion' ofthe Crucible and extend upwardly and I outwardly therefrom so as to open outside base. A'angle-,irons and channel ironsA shown) are the furnace under-the discharge -ends of the tubes K. These wells m serve to permit the refiningv -of e the volatile metallic 'product therein, since any of the heavier metal such ,as lead, which may have been volatilized and carried .out with, the -regular volatile me'- tallic product, will settle out in the wells'm and join the main body of the "same metal which is collected in a molten state at the bottom of Athe crucible., sieparateswells or passages o lead 'upward and outward fromA riveted' or otherwise secured to the inside of the caisson a and extend through 'the body -thefurnace.

of masonry' a, thus'serving at the saine time as braces'or strengthening webs for the metal I caisson and also directly sustaining and supporting thevmasonry itself. The ironbraces cnibeddedjin the masonry also serve to prevent. itifroin floating up when the crucible iiieans for preventing self-induction, due to the ii'on water-jackets, which of course form. a practically closed magnetic circuit around lti\fill.bcobsei\ietl that in the furnace shown, the current. which enters through an electrode extending down through rthe top of the furnace, is normally taken out, not by an electrode at the bottoni as customary heretofore, but by another electrode or electrodes also entering through the top. IIn other words, the current is taken v into and outof the furnace at the same end of the closed yoke formed by the water- -jacket, so that the self-induction from the #water-jacket produced we will say by the.

Otherr rection through the furnace, the watiiujacket surroundingA it would act as the closed core of a transformer, and would give rise to con siderablc current lag land consequent low` power factor.

It will be observed that the furnace shown is especially adapted for use in. connection with a three-phase system .of electrical distribution, one electrode being provided for 'connection to each of the three wires.

feature of the invention consists 11i disposing the several electrodes in a row instead ,of in a close group, the furnace being` of narrow oblong shape so that the side walls may be close to the source of heat. lThere is a limit 'to the thickness of material through which the gaseous zinc may easily escape; and, by the construction above described, the side walls at which the Zinc vapor is condensed and collected may be placed -as close as desired to the electrodes while-at the Sametime the furnace may be made of large capacity by increasing its length. i n' lt will be apparent that as many electrodes may be: provided as the capacity of the furnace requires.

' 'A slag tap s is provided at the topi'of thecrucible `base, the slag being .'drawn off through a hole in the water-cooled *furnace wall, this hole being ordinarily closed by a clay plug.

'The operation of the furnace in siiielting lead-Zinc ore will be apparent.- The charge fed in at the top of the furnace is gradually ous body of material constituting the charge,

and burn .at the top. The charge at the topv is sufficient-ly cool so that the Zinc vapor is condensed before it can escape. The material in the furnace thus gradually becomesenriched in zinc, as it Works doivn, so thatfinally the zinc is suliciently rich to condense as a coherent liquid rather than as zinc dust, and is drained oft' through the tubes or passages K, condensation ytaking .A place in the entrance to said tubes as well as on the adjacent walls. Liquid metal collecting on the walls and draining down, either flows ont of these tubes or passes down te tliejzoiie of greater heataiid is rc-vaporizcd and again condensed, and so finally findsits i way to the outlet-tubes. The liquid metal drawn oli'l through these tubes is collected in the wells m, and"refined as previously described, the heavier metalv settling out and joining that in the bottom OftliecriiCible.

The metals are then ladled out of the re-v spective wells lm, and o.

The consumption of the 4carbon electrodes is lessened b y feeding powdered carbon through the supplemental hopper (Z imm'ediately surrounding said electrodes, so that this powdered carbon, rather than the solid Carbon of the-electrodes, is consumed for the reduction of the ore, the latter being to a great extent shielded from attack.

I prefer to arrange the electrical ConiiectionsA of the furnace as indicated diagrammatically in Fig.` l. The transformers supplying current to the furnace have their secondary coils star-connected and the'three electrodes are connected with the 'three main conductors, ivhile the molten material in the criicible is connected to the neutral `or junction of lthe three star-connected coils. A copper strip t riveted to the inside of the `iron bottom of the Crucible (to which the,

' neutral conductor is connected) extends up into the Crucible to make electrical Coniiection with the molten material therein, thus fo'rmingithe neutral electrode. In the ordinary operation ofthe furnace, llittle if any current flows over. the neutral, but the ai'- 'It will belunderstood that certain features of invention herein set forth will be applicable to furnaces of different types from the one shown, and various modifications may be made in many respects While still making use of one oi more of the essential novel principles oi' details of construction herein disclosed.

I claim:-

l. An electric furnace comprising a crucible base, a fluid-Cooled Wall surmouiiting said base, a tap-opening being provided near the top of the Crucible foi drawing olf the molten product thereiinand body of heatinsulating material exteiiding through said cooled Vall above lthe level ofsaid t,l p, andl having an outlet opening therethrough.

iin electric sinelting furnace having a fluid-cooled wall, a tap opening being provided for removing the molten product, and a tube of heat-insulating material extending -through said wall., above the level of said tap opening', the bore of said tnbe being relatively small aiid an additional water-jacket surrounding said tube.

In an .electric furnace adapted to be heated by the passage of an electric current through a bath of*A slag, the combination of ivater-jacketed. walls, a body of heat-insulatingqiiaterial extending through said walls above the level of said slag bath and having an outlet from the furnace therethrough. 1 4.-. The combination with an electric smell'- ing furnace having a. crucible base surniounted. by a water-jacketed wall, said turnace being adapted to be heated by the passage of electricity througlia bath of molten slag contained iii said ci'ucible base, said Wall having a passage therethrough above the line of said slag bath and a lining of.

heat-insulating material for said passage.

5. An electric furnace having a ciucible base, a Water-Jacket surmounting said base lto form the wall of the furnace, a tap opening being provided near the top of said crucible for removing the molten product from t-lie furnace, -and a plug of carbonaceous niaterial extending through said water-jacket above the level of said tap, said plug having a relatively small opening therethrough.

6. Tliecoinbination with a siiieltiiig furnace, of a .,vater jacket forming an interior Wall adapted to condense metallic vapor in said furnace, a tap opening being provided for removing the molten product, said wall having a passage-therein above the level of said tap opening and iieai the bottoni of said water-jacket, through which the condensed metal may be carried olf, the passage having a lining of material which is a poor conductor of heat; Wliereby the iiietalbeiiig carried off is prevented from congealing and choking said passage.

7. In an electric furnace, the combination with a Crucible base, of a water-jacketed wall surinountingsaid base to forni a smelting chamber, the top of said Chamber being open, a bath of molten conducting material in said crucible, a carbon electrode extending down `through the open top of the furnace and making electrical connection with said molten bath, and a plug of refractory material extending through the'water-jacketed wall above the level of said molten bath, said plug having a restricted hole therethrough adapted to conduct liquid metal through the walls to the exterior of the furnace.

8. In an electric smelting furnace, the combination with acincible base and a wa ter-jacketed wall surmounting said base to form a smelting. chamber, of a thick tube of material which is a poor. conductor of heat, extending through said Watcr-jacketed wall and adapted to carry out the liquid metal` condensed from the volatile vmetallic product of smelting, the said base having a well therein, opening under the mouth of said tube outside the chamber-wall, to. receive the liquid metal from said tube, said well communicating with the lower portion of the crucible inside the furnace, whereby the metal-in saidI well is'kept heated by the moltencontents of said crucible.

9. The combination with a smelting furnace having a crucible base and a smelting chamber surmounting said base; of a` drain arranged to'` carry liquid metal through the walls-of the'smelting chan'iber, the base having a well therein opening under the mopth. of said drain outside the furnace, and Accmm'unicating with the lower portion of the Crucible, whereby the metal in said vWell is kept heated by the molten contents o fsaid cm1-"ibm,

v10. In an electric furnace, the combination with a Crucible base adapted to contain molten product, of a furnace chamber surmounting said base, said chamber having a permanent ope-ning at the top kadaptedl to permit the escape of gas and" a tap opening for removing the molten product, the walls of said chamber being hollow at the top, means for maintaining a flow of cooling liquid in said hollowwalls to cool thecharge at the top and condense the volatile liquid metal toprevent its escape with the non-- condensible gases, said lchamber having an outlet for condensed liquid metal, through 'the side of the furnaceabove the level of vthe condensed liquid metal, the base having two well-s for holding the metallic products,

said wells communicating at the bottom with the lower portion of said crucible and opening outside the wall of the smelting chamber, the mouth of one of said Wells being in position to receive the liquid metal discharged through said opening in the chamber wall.

12. In an electric furnace, the combination with a long and narrow furnace chamber adapted to containr molten conducting material at the bottom, of electrodes in said chamber arranged in a row extending along-A the length of the furnace, said chamber havtion .of said star-connected coils'.

14. In an electric furnace, the combination with a source of alternating current, of a furnace chamber having a-.wall consisting of a water-jacket of magnetic material which forms a substantially-closed magnetic circuitvar'ound the chamber, of two or more electrodes connected for taking thecurrent both in and 'out ofthe furnace through the same end of the .chamber forming the closed circuit, whereby the effect of self-induction by said wall-is neutralized.

15. In an electric furnace, the combination?. v

with a Crucible base, of an iron Water-jacket surmounting said base to form a furnace through the top thereof,.and ada ted to be electrically united in the 'furnace yfa fused bath of 'molten conducting material, said plurality of electrodes being adapted to' con- Vey the current both in and out of the'jfurnace through the top, whereby, the effect of self-induction by the water-Jacket is neutralized. ,f In witness whereof, I hereunto subscribe my name this 6th day of September A. D.,

. FREDERICK T. SNYDER. -Witnessesz u v D. C. TNNER,

A. H. Moena.

chamber, and two or more electrodes supf' ported 1n said furnace chamber passmg- 

